JPS63204878A - Image signal processor - Google Patents

Abstract

PURPOSE:To read an image signal highly accurately even if a mirror or the other are oscillated by scanning several times and averaging the image signal. CONSTITUTION:In a first-time read, an adding gate 15 is closed and an adding circuit 12 outputs its input signal as it is, and in a second-time read, the gate 15 is open, and an image signal read in the first-time read is inputted to the adding circuit 12 from a page memory 13. Therefore, an image signal read in the first time and that read in the second time are added with each other, and its result is held in the page memory 13. Further, in a third-time read, the image signal thus held in the page memory 13 is read out again, and added with a signal read in the third-time read, then stored in the memory 13 again. Thereafter, an output circuit 14 read out an image signal 24 from the memory 13, and the signal is binarized by setting a threshold level 24a between '1'-level and '2'-level.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an image signal processing apparatus that reads an image on a document and obtains a digital image signal for use in copying or other processing.

"Prior Art" Image reading devices such as image sensors are used in copying machines, facsimile machines, and the like to read images on documents and convert them into electrical signals.

The image signal obtained by this image reading device is finally supplied to a printer or the like, and the read image is recorded and reproduced.

Among copying machines, there are two types of copying machines: one that optically guides the image on a document onto a photoreceptor and exposes it to make a copy, and the other that obtains an image signal using an image reading device and supplies it to a printer to make a copy. There is. If the image signal is processed and copied, the image signal is processed in the signal processing circuit,
The copying device can be made multi-functional.

``Problems to be Solved by the Invention'' Now, in scanning for reading images on a document, there are two methods: a method in which a platen glass on which a document is placed remains stationary and an image reading device is driven; There is a method of keeping it stationary and driving the platen glass.

However, in either case, the image signal may be disturbed immediately after scanning starts or during scanning. This occurs because the platen glass, the image reading device, or the mirrors constituting the optical system for guiding the optical image vibrate during scanning, causing the optical image formed on the light receiving surface of the image reading device to waver. When such image signal disturbances are significant, a portion of the copied image becomes unclear and the image quality deteriorates.

The present invention has been made with attention to the above points, and an object of the present invention is to provide an image signal processing device that can correct disturbances in image signals and improve image quality.

"Means for Solving the Problems" The image signal processing device of the present invention includes an image reading device that reads an image on a document and photoelectrically converts it in pixel units to obtain an image signal, and an image reading device that reads an image multiple times. A memory that holds the image signal while repeating the operation, and using the image signal held in this memory, compare and average the corresponding portions of the image signal obtained by the plurality of readings,
It is characterized in that it includes a signal processing circuit that obtains a final image signal.

"Operation" The image signal processing device described above reads an image on a document two or more times, stores the image signal in a memory, and performs averaging processing to obtain an optimal image signal.

Averaging processing refers to obtaining a signal with the highest accuracy by performing an arithmetic average of a plurality of image signals or by majority voting.

As a result, it is possible to obtain a high-quality image signal that cannot be obtained by one reading.

Embodiment FIG. 1 is a schematic configuration diagram showing an embodiment of a copying apparatus of the present invention.

This device includes a platen glass 2 on which a document 1 is placed, a lamp 3 that illuminates an image on the document, mirrors 4a, 4b, and 4C that guide a light image corresponding to the image on the document, and a lens 5. The image reading device 6 includes an image reading device 6 that receives this optical image and performs photoelectric conversion on a pixel-by-pixel basis, and a signal processing circuit 10 that processes the image signal obtained by the image reading device 6.

The image reading device 6 is an image line sensor consisting of a CCD (charge coupled device) or the like. Further, the lamp 3 and the mirror 4a perform a so-called full scan of the entire surface of the original 1 and send the reflected light to the mirror 4b, and the mirrors 4b and 4c perform a so-called half-scan operation to guide the reflected light to the lens 5. The lens 5 causes the reflected light from the mirror 4c to condense on the light receiving surface of the image reading device 6.

The signal processing circuit 10 includes a correction circuit 11, a digital addition circuit 12, a page memory 13, an output circuit 14, and an addition gate 15.

The correction circuit 11 is a circuit that converts an analog image signal read by the image reading device 6 into a digital image signal, and further performs shading correction and the like. Addition circuit 12
is a circuit that adds the image signal manually input from the correction circuit 11 and the image signal input from the addition gate 15 and outputs the result. The page memory 13 is a memory that stores image signals for one page of read images. This memory stores, for example, an image signal of 2 bits and 4 levels per pixel. The output circuit 14 is a circuit that binarizes the image signal held in the page memory 13 after completing certain processing and outputs it to an external circuit. Further, the addition gate 15 is a gate that is opened when performing addition processing between the read image signal and the image signal stored in the page memory 13.

The image signal processing apparatus of the present invention having the above configuration operates as follows.

In this embodiment, it is assumed that, for example, an image signal for one pixel is processed in the correction circuit 11 by comparing the pixel density with a certain threshold level and converting it into a binary signal.

First, in the first reading, the output signal of the image reading device 6 passes through the correction circuit 11 and the addition circuit 12 and is held as it is in the page memo 'J13.

At this time, the addition gate 15 is closed, and the addition circuit 12 operates to output the input signal as it is.

In the second reading, the addition gate 15 opens, and the image signal read the first time from the page memory 13 is input to the addition circuit 12. As a result, the image signal read the first time and the image signal read the second time are added, and the result is held in the page memory 13.

Further, in the third reading, the image signal held in the page memory 13 is read out again, added to the image signal read in the third time, and the image signal held in the page memory 13 is read out again.
will be stored again.

FIG. 2 shows examples of an image signal 21 read the first time, an image signal 22 read the second time, and an image signal 23 read the third time (FIGS. 2a-C).

The contents of these signals are inconsistent due to vibrations of mirrors and the like.

The image signal 24 (FIG. 2 d) which is added and stored in the page memory 13 has 2 bits per pixel, 0", "1".
The signal has four levels: ”, “2”, and “3”.

Here, the output circuit 14 reads out this image signal 24 from the page memo IJ l 3 and outputs the image signal 24 to the threshold level 24.
By setting a between “1” and “2”, the image signal 2 (I
Perform t conversion.

As a result of the above, the finally obtained image signal 25 (Fig. 2 e
) can be used as the image closest to the image on the original document, and high-quality images can be recorded using an external circuit ().

"Modification" The image signal processing device of the present invention is not limited to the above embodiment.

If the image signal is not binarized but has gradation, the image signals may be simply added and then arithmetic averaged to obtain the final image signal. Further, scanning is not limited to three times, but may be performed twice or four times or more.

"Effects of the Invention" According to the image signal processing device of the present invention described above, since the image signal is averaged by scanning several times, it is possible to read the image signal with high precision even if there is vibration of a mirror or the like. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the image signal processing apparatus of the present invention, and FIG. 2 is a signal waveform diagram of the image signal. 1... Original, 6... Image reading device, 1
0...Signal processing circuit, 13...Memory. Applicant: Fuji Xerox Co., Ltd. Agent

Claims (1)

[Claims] An image reading device that reads an image on a document and photoelectrically converts it pixel by pixel to obtain an image signal, a memory that holds the image signal while this image reading device repeats reading operations multiple times, and an image held in this memory. An image signal comprising: a signal processing circuit that uses the signal to compare and average corresponding portions of the image signals obtained by reading the plurality of times to obtain a final image signal. Processing equipment.